Yellow spots on Phal leaves!

[Lori Ferens]

Hello! I am a new owner of 3 small phals (a gift from my aunt - they are all what she called "babies" off a "mother" plant). One is blooming and they all have about 4 strong leaves each. I have had them since December and they have all been growing well - the leaves have been getting bigger and one plant has a new leaf starting.
My problem is that I noticed this week the newest (top-most) leaf of each plant has started to develop a yellow area. The leaves are still firm and not wilting, but I'm worried!
They are in small pots, in sphagnum moss and the pots sit on pebbles in a tray with water to add humidity. I water approx. once a week, checking to make sure the moss doesn't dry out. They get plenty of indirect light, and the temperature of the room is steady, so there are no drafts. They haven't been moved since I brought them home in December.
Any ideas?

[jerrymeola]

damage to the top most leaf is a bad sign. Lower leaves can yellow and die naturally but the newest leaf sounds like root damage. From your description it sounds like too much water.

Watering once a week is usually about right but possiby too much for your home. I would let it dry out. Go two weeks without water. If you had more experience I would suggest removing the plant and examining the roots, but you would not know what to look for and may do more damage.

I like sphagnum for phals but it does hold a lot of water and does not need to be watered very often.

Another possibility is that you may have been watering over the leaves. You should not allow water to stay in the crown of the plant. This causes rot and the leaves will fall off. Always water into the medium on the side of the plant.

[Lori Ferens]

Thank you for your advice Jerry. Since I asked my question, I have noticed that the newest leaf on one plant has developed a white thin spot. I may be over-watering as you suggest, so I'll try to hold off for a little longer and see if it helps. Usually I test the moss to see if it feels dry and try not to let it get "crispy" - how dry should it get? I try not to get any water on the crown of the plants so I don't think that would have anything to do with it. They are still quite small (the plants and the pots) and I worry that two weeks without water might be too long? What do you think?

[Ellen]

A white thin spot on the leaf could be sunburn. Is your plant in direct sun? Waiting 2 weeks to water a plant in a small pot could be too long. One way to tell if your plant needs water is by how much the pot weighs. Before you water the plant, when you know it is completely dry, get a feel for how much the pot weighs. Then feel the weight again after watering. You should be able to remember the different weights and judge whether the medium is dry just by lifting the pot.